Although applicable to any fibre composite components, the present invention and the problem on which it is based will be explained in greater detail hereinafter with reference to planar, carbon fibre reinforced plastic (CFRP) components reinforced with stringers, for example skin shells and shell components for an aircraft.
It is generally known that CFRP skin shells can be reinforced with CFRP stringers in order to withstand the loads which occur in aircraft, with as little additional weight as possible. In this case, a distinction is basically made between two types of stringers: T-stringers and omega-stringers.
The cross-section of T-stringers is composed of the base and the web. The base forms the connecting surface to the skin shell. The use of skin shells reinforced with T-stringers is widespread within the aircraft industry.
Omega-stringers have an approximately hat-shaped profile, of which the lower ends are connected to the skin shell. Omega stringers may be either adhesively bonded, once cured, to the skin shell which is also cured, cured wet-on-wet at the same time as the shell, or adhesively bonded to the cured shell when wet. The first case is most desirable since it is more favourable with regard to the technical processes involved. However, in order to produce skin shells reinforced with omega-stringers, it is necessary to use support or mould cores in all of the various processes described in order to support the hollow profile during the production process. Skin shells with omega-stringers provide the advantage over T-stringers of having better infiltration properties during an infusion process carried out in order to introduce a matrix, for example an epoxy resin, into the fibre semi-finished products. Furthermore, compared with other cross-sectional shapes, this cross-sectional shape offers a good ratio between weight and moment of inertia.
However, when producing fibre composite shells reinforced with omega-stringers, there is the drawback that the material currently used for the support or mould core is expensive and is difficult to remove once the omega-stringers have been formed, such that any material remaining in the stringers contributes to the weight of the fibre composite component and thus to the weight of the aircraft in a disadvantageous manner.
Different production methods may be used to produce hollow components using fibre composite construction methods, the use of which production methods is dependent, inter alia, on the general product-specific requirements, such as production rate, shape or cross-section, requirements regarding surface configuration or strength. Examples of the main production methods are as follows:                Blow hose method        Non-permanent moulding (chemical, mechanical or thermal removal methods)        Cores remaining in the component (for example foam made of synthetic resins)        rotational moulding method        filament winding method        
However, owing to specific features, the majority of these methods are, during the progression thereof, only suitable for the production of compact components having similar measurements in all dimensions and a relatively small linear extent. In order to produce components, the measurement of which in one axis is considerably greater than that in the other axes, a blow hose method has primarily been used previously on an industrial scale.
In order to produce fibre composite components which must satisfy strict requirements with regard to component weight and mechanical load, it is necessary to shape and compact the laminate by applying a planar pressure to the laminate during the curing process. With conventional production methods, a component is thus shaped by inserting the different woven fabric layers into a female mould. Once all the reinforcing layers of the laminate have been inserted into the mould, these components are saturated with resin, depending on the selected shape of the semi-finished product and the production method, or in the case of production with prepreg fibres, these are placed in the mould. Next, once auxiliary materials such as ventilation fabrics and separating films have been applied, an airtight film is placed on the mould and hermetically sealed onto said mould. Once the air inside the vacuum has been vacuumed off, the component can be pressed in a planar manner and the correct fibre to matrix ratio can be achieved and the laminate can also be produced with no fibre ridges during the curing procedure. However, a prerequisite for this production method is that the surface of the entire laminate should be accessible on one side. When producing a hollow component, this process is not possible owing to the restricted access to the inside of the component after production.
The most significant drawbacks of the aforementioned methods are as follows:                Poor surface quality inside the component when producing a component using an excessively long blow hose. In this regard, FIG. 1 shows an example of a conventional method for producing a hollow reinforcing component 2 having a trapezoidal inner cross-section 13. The hollow reinforcing component 2 is attached as a stringer in order to reinforce a shell component 3. An excessively long blow hose 12 having an originally circular cross-section is arranged inside the hollow reinforcing component 2. When the hose is inflated, resin accumulations 15 are created by the formation of folds. Owing to these resin accumulations 15, problems regarding an increased likelihood of cracks as a result of the unreinforced resin result in addition to problems regarding a poor fibre:matrix ratio.        The blow hose 12 is configured as a hose having a round cross-section. When the blow hose 12 is pressurised, said blow hose 12 rests against the inner walls of the component 2 and of the uncured shell laminate 3. The blow hose 12 cannot completely fill the corner regions. The blow hose 12 is thus arched and resin accumulations 15 are formed. The lack of pressure on the laminate may lead to the formation of ridges and localised excesses of resin (undulations) in the laminate.        Owing to the blow hose 12 not sufficiently abutting localised portions, fibre ridges may be produced.        The production method is complicated further by the complex integration of the blow hose 12 into the mould and the component.        The process poses an increased risk when a thin-walled blow hose 12 is used, owing to the hose becoming arched in the corners of the component, thus causing the hose material to expand excessively until it bursts, possibly destroying the entire component.        Labour-intensive removal and production of the core.        Production of components having narrow radii in cross-section or of a specific shape is not possible with the methods described.        If auxiliary production materials remain in the component, the weight of the component increases whilst the mechanical values of the component are not increased at all, or are only increased slightly by the auxiliary material.        
Accordingly, one object of the present invention is to provide a method for producing an integral, reinforced fibre composite component comprising at least one hollow reinforcing component made of fibre composite material and a shell component.